Created
June 26, 2020 19:39
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| /** | |
| * @author luxz | |
| * @date 2020/6/27-3:31 AM | |
| * 如果执行乐观读操作期间，存在写操作，会把乐观读升级为悲观读锁 | |
| */ | |
| public class Point { | |
| private int x, y; | |
| final StampedLock sl = new StampedLock(); | |
| int distanceFromOrigin() { | |
| // 乐观读 | |
| long stamp = sl.tryOptimisticRead(); | |
| // 读入局部变量，读入的过程中数据可能被修改 | |
| int curX = x, curY = y; | |
| // 判断执行读操作期间，是否存在写操作，如果存在，则sl.validate返回false | |
| if (!sl.validate(stamp)) { | |
| // 升级为悲观读锁 | |
| stamp = sl.readLock(); | |
| try { | |
| curX = x; | |
| curY = y; | |
| } finally { | |
| // 释放悲观读锁 | |
| sl.unlockRead(stamp); | |
| } | |
| } | |
| return (int) Math.sqrt(curX * curX + curY * curY); | |
| } | |
| } |
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